This invention relates in general to molten salt electrochemical systems and in particular to such systems using molten chloroaluminate solvents that melt below 200.degree.C, an aluminum metal anode and positive oxidation states of either iodine or sulfur as the active cathode material.
Present aqueous and organic electrolyte electrochemical systems do not have the high conductivity and power densities required in certain applications, as for example, in electric vehicles. Attempts have been made to use a molten salt electrolyte because of its high conductivity but these attempts have not been entirely satisfactory in that they have required a temperature above 350.degree.C.
It has been suggested in the art that the molten salt electrochemical system could be improved by the use of a low melting molten chloroaluminate as for example, a mixture of AlCl.sub.3 and NaCl as the electrolyte and solid aluminum as the anode. That is, the molten chloroaluminate has a low liquidus temperature and high conductivity while aluminum as the anode is of potential advantage since aluminum is relatively inexpensive and has a small equivalent weight. As the cathode for such a system, gaseous chlorine has been used to obtain high energy densities and reasonable EMF's of about 2 volts, but problems associated with the use of gaseous chlorine make such an electrochemical system less desirable. U.S. Pat. No. 3,573,986 issued Apr. 6, 1971 to Jacob Greenberg for "HEAT ACTIVATED CELL" teaches the use of elemental sulfur as the cathode for such an electrochemical system or battery but such a system is not satisfactory in that the EMF is 1.2 volts which is too low.